Autori: Sylvester, Z., Lowe, D.R

Editorial: Middleton, G., Kluwer Academic Publishers, Encyclopedia of Sediments and Sedimentary Rocks, p.294-296, 2003.

Rezumat:

Fluid escape structures, sedimentary structures that form during escape of pore fluid from loose, unconsolidated deposits, are briefly reviewed. Most fluid escape structures are postdepositional in origin. However, some vertical fluid escape structures and convolute lamination probably have formed during sedimentation. The postdepositional features may represent modified primary or previously formed postdepositional structures or entirely new structures. Deformation may result directly from (1) pore-fluid movement, from (2) current shear, or (3) gravity forces that act on liquefied sediment that has lost a significant part of its strength due to fluid escape. In most cases, the pore fluid is water, and we talk about water escape structures. However, volcaniclastic deposits frequently have fluid escape structures that are the result of gas escaping from sediments of dry pyroclastic flows. In general, fluid escape structures are most common in rapidly deposited and poorly sorted fine- to medium-grained sands and rare in relatively slowly deposited and texturally mature deposits.

Cuvinte cheie: Fluid escape structures, sedimentary structures, dish and pillar structures